SCL-70 antibody test

Your doctor may order this test if he/she suspects that you have symptoms of scleroderma.

Depending on the area affected, the symptoms associated with scleroderma are as follows:

• Skin symptoms: 

  • Raynaud phenomenon (a condition in which the fingers or toes turn blue or white in cold temperatures)
  • Hair loss
  • Small white lumps of calcium under the skin that ooze a white material like toothpaste
  • Stiffness and tightness of skin of fingers, hands, forearm and face
  • Sores (ulcers) on the fingertips or toes
  • Tight and mask-like skin on the face
  • Telangiectasia (small, dilated blood vessels seen as red blotches on the face or at the edge of fingernails)
• Bone and muscle symptoms: 
  • Joint pain 
  • Swelling and stiffness that reduces movement, usually in the hands
  • Numbness and pain in the feet
• Digestive symptoms:
  • Difficulty swallowing
  • Constipation
  • Diarrhoea
  • Heartburn
  • Bloating after meals
  • Problems controlling defecation 
• Lung symptoms:
  • Dry cough
  • Increased risk of lung cancer
  • Shortness of breath
  • Wheezing
• Symptoms related to heart problems: 
  • Abnormal heart rhythm
  • Reduced heart function
  • Fluid around the heart
• Kidney and genitourinary problems:
  • Kidney failure
  • Erectile dysfunction in men
  • Vaginal dryness in women

You do not need to fast before this test. Some medicines like aminosalicylic acid, tetracycline, isoniazid, methyldopa, penicillin, propylthiouracil and streptomycin may increase the level of SCL-70 antibodies in the body. If you are on any medications, please inform your doctor before the test.

A blood sample is needed for this test. Your healthcare practitioner will withdraw the required amount of blood from a vein in your arm. 

This procedure typically takes less than a few minutes. If blood tests make you feel dizzy or faint, please tell your doctor or nurse so that they can look after you better. After the test, you may get a bruise at the needle insertion site, it will fade away in a few days.

Normal results: 

A normal test result is reported as negative. SCL-70 antibody levels less than or equal to 29 AU/mL (arbitrary units per millilitre) are considered normal. However, a normal result does not necessarily rule out the possibility of scleroderma. Your doctor will interpret your results based on your health history, symptoms and the results of other autoantibody tests.

Abnormal results:

An abnormal test result is reported as positive. The following readings indicate an abnormal result:

• Equivocal (a test result that is between negative and positive results): 30-40 AU/mL
• Positive: 41 AU/mL or greater 

Abnormal results indicate the following conditions: 

• Scleroderma
• CREST syndrome: A limited form of scleroderma characterised by calcium deposits in the skin, Raynaud phenomenon, oesophageal dysfunction (difficulty swallowing), sclerodactyly (skin tightening on the fingers) and telangiectasia

SCL-70 antibodies may also be detected in other autoimmune diseases, such as systemic lupus erythematosus (SLE).

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.